quantification and optimization of overall desirability ...

ICETT 2014 ISBN: 978-93-5156-700-4

INTERNATIONAL CONFERENCE ON EMERGING TRENDS IN TRADITIONAL & TECHNICAL TEXTILES April 11th - 12th 2014, NIT JALANDHAR ( INDIA)

QUANTIFICATION AND OPTIMIZATION OF OVERALL DESIRABILITY TO ACHIEVE VALUE ADDED GARMENT *

K V P Singh, A Das2 and Raul Fangueiro3

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2

Department of Textile Technology NIT Jalandhar, Punjab; Department of Textile Technology IIT Delhi, India; 3 Department of Textile Engineering University of MINHO Portugal

Keywords: Comfort, Handle, desirability, FAST, DREF- III, Friction spun yarn.

1. Introduction As per the global scenario, physiological comfort is very basic and necessary property of the fabric. The fabrics with higher level of comfort values have a tremendous scope from the point of view of comfort in the garment industry. The comfort has been an inherent feature of the knitted textiles. To further increase the softness in knitted fabric, twistless yarns are used. As compared with that of conventional spun yarns, their strength largely depends on the amount of twist but it has the disadvantage of imparting a harsh feel to the fabric. Once the twistless yarn has been assembled in a fabric structure, the compacting forces created by the fabric structure itself hold the systems together. Hence, it is quite possible to produce a twistless knitted fabric with improved parameters of physiological comfort, which can be beneficial for apparels. Among the modern high technologies for producing spun yarns, friction spinning has some advantages over the others due to lower production cost. But its main disadvantage is the harsh feel due to the wrapper fibres of the sheath. In order to increase the comfort-related properties of friction-spun yarn, Merati and Okamura used hollow yarn. They succeeded in getting the enhanced comfort with hollow yarn but they were unable to minimize the harsh feel in fabric. Das and Ishtiaque used twistless friction-spun yarns in weft to improve the comfort characteristics of fabrics. However, there is still a need to improve comfort characteristics of friction spun yarn with minimum harsh feel. The present work was therefore undertaken with an objective to prepare twistless friction-spun yarn with minimum harsh feel and enhanced cum optimized physiological comfort-related properties keeping in view the handle properties. Moreover, the state of comfort can only be achieved when the complex interactions between a range of physiological, and physical factors have taken place in a satisfactory manner. The quantification and optimization of desirability of both comfort and handle is done to achieve the overall desirability of value added garment.

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Methodology The prepared plain knitted samples of both optimized modified friction spun yarn and conventional friction spun yarn were tested and compared for analysis with an objective to quantify and optimize the desirability of both comfort and handle in order to achieve the overall desirability of an ideal fabric to achieve value added garment. (A. Hadj Taieb, S. Msahli, and F. Sakli, 2010) To fulfill the objectives of the study, the methodology is planned out in the following manner: 1. Preparation of yarn samples. 2. Preparation of the circular knitted fabric from yarn samples. 3. Testing the knitted fabrics for desired properties. 4. Response surface method for data analysis. 5. Development of regression model equations of different responses of modified friction spun yarn. 6. Optimization of modified friction spun yarn. 7. Development of a model of an optimized modified yarn. 8. Comparative study of conventional friction spun yarn with optimized modified yarn and testing of the hypothesis. 9. Quantification and optimization of desirability of comfort and handle. 10. Quantification and optimization of overall desirability of best fabric.

3.

Physiological comfort The state of comfort can only be achieved when the complex interactions between a range of physiological, and physical factors have taken place in a satisfactory manner i.e.

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ICETT 2014 ISBN: 978-93-5156-700-4


Desirability of Physiological comfort = f (a, b, c, d, e) at specific atmospheric conditions with predefined constraints. Where; a = air permeability; b = thermal conductivity; c = wicking; d = water absorbency; e = water vapour permeability. Objective evaluation of the above mentioned responses of physiological comfort as per the functional requirement of apparel and its simultaneous objective optimization is known as the desirability of physiological comfort. When, there are ‘m’ responses then overall combined desirability is calculated by considering; ‘DC’ = (d1, d2, d3, ----- d5)

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(Desirability function for physiological comfort)

Where; DC = combined desirability of overall responses of physiological comfort d = desirability of specific response ‘Y’ as per specific end use;

4. Handle ‘Fabric handle evaluation’ = ƒ (a, b, c, d, e, f, g, h, i, j) At specific atmospheric conditions with predefined constraints. Where; a = Relaxation shrinkage; b = Hygral expansion; c = Formability; d = Extensibility; e = Bending rigidity; f = Shear rigidity; g = Thickness; h = Surface thickness; i = Released surface thickness; j = Weight When, there are ‘m’ responses then overall combined desirability is calculated by considering; ‘DH’ = (d1, d2, d3, ----- d10)

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(Desirability function for handle) Where; DH = combined desirability of overall responses of handle d = desirability of specific response ‘Y’ as per specific end use; Maximum enhancement in physiological comfort related properties of fabric with predefined constraints in desired atmospheric conditions and microclimate for specific end use along with achievement of all FAST parameters in good zone of fabric finger prints is termed as desirability of handle. 4.1 Overall Desirability of physiological comfort and handle It is a useful approach for optimization of multiple responses of physiological comfort and handle by using the simultaneous optimization technique. Desirability of Comfort and Handle is denoted as D C & DH . DO= (DC . DH )

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Where DO = Overall Desirability is the desirability of value added garment and is defined as simultaneous optimization of comfort, handle and garment-fit as per its specific end use with known constraints It can be compared with Total Hand value by comparing individual desirability of comfort & handle with Primary Hand values (PHV). Total Hand Value (THV) considers only handle properties but Overall Desirability (Do) considers both the parameters of comfort and handle. Optimized yarn: Optimized yarn is a unique modified friction spun yarn, whose physiological comfort related responses are simultaneously optimized to avoid clamminess in summer. Value added garment from ideal fabric: It is a garment prepared with ideal fabric. ‘Ideal Fabric’ can be defined as a fabric which satisfies all the parameters or responses of both comfort and handle simultaneously required for the specific end- use as per the desirability. Best- Fabric keeps on changing due to fabric properties required for specific end-use After the prediction of values of considered factors and responses, an optimized yarn is developed with maximum desirability value, is converted into a knitted fabric and garment. Objective evaluation of the above

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ICETT 2014 ISBN: 978-93-5156-700-4


mentioned responses of physiological comfort fabric handle as per the functional requirement of the apparel and its simultaneous objective optimization to achieve a unique value is known as the overall desirability of best fabric. 4.2 Evaluation of Overall Desirability of ideal fabric As, overall desirability of garment is; Do= (DC. DH) DC = 0.577 DH = 0.570 Therefore overall desirability

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Do = (0.577 x 0.570) 1/2 = (0.32889) = 0.5734 If the overall desirability of fabric will be 0.5734 than we will be able to achieve the value added garment known as an ‘Ideal fabric’.

5. Conclusion In this work, Physiological Control System (PCS) of both comfort & handle is being upgraded to Engineering Control System (ECS) by conversion of conceptual model to a mathematical model. Re-optimization of both comfort and handle by reverse engineering process, to identify the best sample with maximum overall desirability of ideal fabric to achieve value added quality garment. Optimization & quantification of the responses in good zone of FAST fabric finger prints to achieve a unique value known as an optimized value as per engineering control system by developing a back-propagating mathematical model. Achievement of best fabric, in terms of simultaneously re-optimized physiological comfort and handle properties, for its conversion into garment. Best sample is identified, which satisfies both the parameters of comfort and handle. In case of any technical problem during garment conversion after reoptimization; suitable solution to it should be provided. The ‘best fabric’ satisfies all the parameters or responses of both comfort and handle simultaneously required for the specific end- use as per the desirability and keeps on changing due to fabric properties required for specific end-use. Optimized value of each response of comfort and handle can be treated as Primary Hand Value (PHV). The desirability of both comfort and handle can be treated as Total Hand Value (THV). Further optimization of desirability of comfort and handle will provide a unique value co-relating comfort and handle. Total Hand Value (THV) considers only handle properties but overall desirability (D o) considers both the parameters of comfort and handle. Hence by conversion of Physiological control system to Engineering control system the overall desirability can be achieved. After comparing the value added garment; with the garment made from conventional friction spun yarn; significant decrease in bending rigidity has taken place, keeping formability in range.

6. Corresponding Address K V P Singh, Department of Textile Technology, NIT Jalandhar, Punjab, India

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